| ⊢ | (while w do f) ; g ≡if w then f ; (while w do f) ; g else g | WhileChopEqvIf | 
Proof:
| 1 | ⊢ while w do f ≡if w then f ; (while w do f) else empty       | |
| 2  | ⊢ (while w do f) ; g ≡                    | |
| if w then (f ; while w do f) ; g else empty ; g                   | ||
| 3  | ⊢ (f ; while w do f) ; g ≡ f ; (while w do f) ; g             | |
| 4  | ⊢ empty ; g ≡ g                                             | |
| 5  | ⊢ (while w do f) ; g ≡if w then f ; (while w do f) ; g else g | 
qed